Major drivers behind increased efforts in product development are the increased competition due to globalisation and the urgent transformation of society towards sustainability. Furthermore, the average product lifetime has been compressed significantly over the last decade. Due to these trends, there is increasing demand for an efficient product development process. Cutting time-to-market, reducing costs and increasing quality are widely accepted as key factors to successful product development. Consideration of sustainability aspects in product development is also becoming increasingly important. Methods and tools that are useful also for small and medium sized enterprises are of particular importance for the Swedish industry.

This thesis suggests a definition of lean prototyping and points to its potential for supporting efficient product development. This is done through two case studies: a soil compactor machine treated as a multi-body system and a water jet cutting machine treated as a mechatronic system. Lean prototyping is defined as a coordinated approach to experimentation with the purpose of achieving cost-efficient and accurate enough prediction of product characteristics to support optimisation and well-informed design decisions during product development, especially in the early stages. This often involves an iterative search for and use of a suitable combination of virtual and limited physical prototypes as well as the reuse of knowledge from previous projects. The case studies are performed in cooperation with one small and one medium sized company, indicating the usefulness of the approach for different product types as well as for different company sizes.

More specifically, the validated multi-body model of the soil compactor machine describes the dynamics of the machine satisfactorily and the optimisation study shows a significant potential for improved compaction capacity. This potential would not likely been found through traditional physical prototyping. The related comparative study of contact transition conditions is a contribution to consistent impact modelling in multi-body dynamics in general. The real-time virtual machine concept for simulation of the water jet cutting machine, including detailed mechanical component models, is unique. The fully automated concept implementation makes it a promising base for multidisciplinary design optimisation of the water jet cutting machine, and probably of mechatronic products in general.